Glass that reads the wallpaper
KWin's blur can't help a desktop widget. The widget lives inside the same plasmashell window that paints the wallpaper, so there is nothing behind it to composite. Each card reads the wallpaper instead, crops it to its own spot on screen, blurs that and masks it to the card.
A second, magnified copy sits only in the border ring, which gives the edge its slight refraction. Slideshow wallpapers have no single image to sample, so those fall back to a plain tint.
Screen Time needed a backend
Most widgets are a single QML file. Screen Time is the exception: a small KWin script fires on every window-focus change and tells a Python daemon, running as a systemd user service, which app you switched to.
The daemon keeps seconds per app per hour in SQLite, skips time when you're idle by asking the screensaver, and the widget polls it every 15 seconds.
Nothing to sign up for
Weather comes from Open-Meteo, so there's no API key. Now Playing talks to any MPRIS player over D-Bus. The installer checks dependencies first, registers each widget and reloads the shell, and every widget has its own Configure page for colours, blur and refresh rates.